Method of producing soy protein concentrates

ABSTRACT

A method of producing or recovering improved, soy protein concentrate compositions, suitable for use in food products for humans, consisting essentially of an edible, nutritious, uniformly palatable, debittered, bland, proteinaceous composition free of undesired, characteristic beany taste or flavor, which involves combining (a) highly proteinaceous, soy protein isolate recovered from a liquid extract from an extraction of soybean material at a pH above the vicinity of the isoelectric pH of the glycinin content, with (b) fibrous residue recovered from said last-mentioned extraction, to produce an improved, soy protein concentrate.

Unite States atent [4511 Jan. 1972 Sair [54] METHOD OF PRODUCING SUYPROTEIN CONCENTRATES [72] Inventor: Louis Sair, Evergreen Park, Ill.

[73] Assignee: The Griffith Laboratories, Inc, Chicago,

Ill.

[22] Filed: Sept. 20, 1968 [21] App]. No.: 761,282

[52] U.S. Cl ..99/17 [51] Int. Cl. ..A23j 1/14 [58] Field of Search..99/14, 17, 98, 99

[56] References Cited UNITED STATES PATENTS 2,284,700 6/1942 Wahlfoss..99/98 X 2,88 L076 4/1959 Sair ..99/14 Primary ExaminerA. LouisMonacelll Assistant ExtzminerWilliam Andrew Simons Att0rneyMerriam,Marshall, Shapiro & Klose A method of producing or recovering improved,soy protein concentrate compositions, suitable for use in food productsfor humans, consisting essentially of an edible, nutritious, uniformlypalatable, debittered, bland, proteinaceous composition free ofundesired, characteristic beany taste or flavor, which involvescombining (a) highly proteinaceous, soy protein isolate recovered from aliquid extract from an extrac tion of soybean material at a pH above thevicinity of the isoelectric pH of the glycinin content, with (b) fibrousresidue recovered from said last-mentioned extraction, to produce animproved, soy protein concentrate.

ABSTRACT 12 Claims, No Drawings METHOD OF PRODUCING SOY PROTEINCONCENTRATES This invention relates to improved, edible, nutritious,uniformly palatable, bland, debittered, particulate, soy proteinconcentrate compositions freed of undesired, characteristic beany tasteor flavor. These improved, concentrate compositions are particularlyuseful in food products for humans. The present invention also relatesto methods for preparing or recovering such improved, concentratecompositions.

Soybean materials, including flour or flakes, provide one of thecheapest and best sources of essential protein.

Soybean flour or flakes, for example, have been used in a limited mannerin the preparation of ground meat products as a fat emulsifier andwater-binding agent.

Defatted soybean grits (hulled, coarse grain soybean product), includingthose produced from soybean flakes, have also been mixed with groundmeat products. Soybean grits constitute a very nutritional productcontaining about 50 percent by weight of protein. Soybean grits blendwell with meat products, and when meat products having grits are cooked,the resulting products retain their desired character and as a result ofthis, the feel and texture of such products in the mouth are excellent.in many respects, soybean grits are an ideal extender to meat products,since the grits aid in retaining or binding the natural water of themeat and binds such products during cooking. When 5 pounds of soybeangrits, for example, are added to 100 pounds of ground meat, one may addan additional to pounds of water and still have a very suitable,commercial meat patty from the standpoint of consistency and appearance.

One of the greatest obstacles to the general use in this country ofsoybean materials as a direct source of human food products, is thecharacteristic bitter beany taste or flavor; however, this has notpresented as severe a restriction in Asiatic countries. A great amountof research has been conducted to try to eliminate this undesiredcharacteristic, and many approaches have been used.

One approach involves the production of a soy protein isolate whereinsoybean flakes are extracted or washed with a dilute aqueous alkalinesolution. Following extraction, the flakes are subjected tocentrifugation or screening to provide for the recovery of an insoluble,fibrous residue which is separated from the liquid, soy protein extract.The separated, fibrous residue has been used with other materials asanimal feed, The liquid extract is subjected to an acid-precipitationstep to produce a precipitated, soy protein isolate or cured having a pHof the order of about 4.5. The precipitated, isolate curd is subjectedto a filtering or separation step which separates the soluble whey fromthe insoluble, isolate curd which may be in the form of a filter cake orwet mass. The iso late is washed and diluted with water, andneutralized. Alternatively, the soy protein isolate may be dried as suchor in the neutralized form. The resulting soy protein isolate maycontain, for example, about 90 percent by weight protein on a dry basis.

Another approach, as shown in U.S. Pat. No. 2,881,076, involves theadjustment of the pH of soybean materials to the vicinity of theisoelectric point, followed by extensive washing with water to removeretained beany taste or flavor conferring constituents and provide anoutstanding, soy protein concentrate having a minimal level of undesiredbeany taste or flavor, odor and color.

More specifically, U.S. Pat. No. 2,881,076 describes an unobviousprocess for preparing or recovering an improved, soy protein concentratewhich requires that soybean material, for example, in the form ofdeoiled or defatted flour or flakes, be subjected to the dissolvingaction of water having a pH in the vicinity of the isoelectric pH of theprotein content of the soybean material, and that the insoluble solidsin the form of an essentially insoluble slurry be separated from theresulting solution. The insoluble solids are then washed. The purpose ofthese steps is to remove undesired, characteristic beany taste orflavor, odor and color conferring ingredients. A preferred embodimentinvolves neutralizing the insoluble, soy protein material by adding anedible, alkaline agent to the insoluble protein slurry to raise its pH.The resulting concentrate slurry may be dried (e.g., spray dried).

By utilizing the process of U.S. Pat. No. 2,881,076, the soluble sugarsand nitrogen-containing materials soluble in the vicinity of theisoelectric pH, and characteristic beany taste or flavor, odor and colorconferring bodies are removed, which results in a soy proteinconcentrate product having a protein content, on a dry basis, of about70 percent or higher. Such a concentrate product has a bland anddebittered taste, light color, and when suspended in water, developsviscous dispersions having good emulsifying and water-bindingproperties.

The dried, bland, soy protein concentrate of U.S. Pat. No. 2,881,076 hasmet with great acceptance, has high protein content (e.g., about 70 to73 percent by weight on a dry basis), and offers the combined andunobvious advantages of having been freed of undesired beany taste orflavor, odor and color conferring ingredients and having superioremulsifying and water-binding properties, particularly in emulsifiedmeat products.

However, the soy protein concentrate of U.S. Pat. No. 2,881,076 has avery small residual level of beany taste or flavor which has restricted,to some degree, its use in bland,

delicate foods for humans, such as milk products and desserts.

l have discovered that in producing a soy protein concentrate, more ofthe undesired, characteristic beany or chalky taste or flavor, beanyodor and color conferring bodies are removed from soybean material byextracting the soybean material at a pH above the vicinity of theisoelectric pH of the glycinin content than results from extraction at apH in the vicinity of the isoelectric pH of the glycinin content.

The extraction at a pH above the vicinity of the isoelectric pH of theglycinin content effectively removes undesired beany taste or flavorbodies, and in addition extracts desired, soluble protein. In thisextraction, for example, about 35-38 percent by weight of the originalsoybean material is in a soluble form which can be recovered as soyprotein isolate which is free of undesired beany taste or flavor bodies,and about 33-37 percent by weight of the original soybean material isinsoluble and can be recovered as fibrous residue having polysaccharidesand insoluble protein and which is likewise free of undesired beanytaste or flavor bodies.

The soluble protein may be precipitated and ultimately recovered fromthe extract as soy protein isolate which is free of such undesired beanytaste or flavor bodies, by reducing the pH of the extract to a pH in thevicinity of the isoelectric pH of the glycinin content.

Since the recovered fibrous residue and protein isolate, particularlywhen washed, are both free of the undesired, characteristic beany tasteor flavor, l have found that they can be combined effectively andeconomically to produce an improved, soy protein concentrate.

Thus, the insoluble, fibrous residue which has been used heretofore inanimal feed can be combined effectively, in desired proportions, withthe more proteinaceous, insoluble, soy protein isolate, and the combinedproduct may be neutralized to a pH within the range of from about 5.5 to10.5, and dried, to provide an economical, improved, highlyproteinaceous, soy protein concentrate suitable for human consumptionthat is free of undesired, characteristic beany or chalky taste orflavor, and beany odor and color.

My invention takes advantage of the fact that the soluble, liquidextract and/or wash resulting from (a) the extraction of soybeanmaterial at a pH above the vicinity of the isoelectric pH of theglycinin content, and (b) the precipitation of the soy protein isolateat a pH in the vicinity of the isoelectric pH of the glycinin content,includes and very effectively removes the undesired, characteristicbeany or chalky taste or flavor, and beany odor and color conferringingredients both from the recovered, fibrous residue and the soy proteinisolate, respectively. This enables one to combine the fibrous residuewith the soy protein isolate to provide economically an improved,edible, nutritious, uniformly palatable, bland, debittered, soy

protein concentrate which is free of undesired, characteristic beany orchalky taste or flavor, and beany odor and color, and is suitable foruse in food products for humans, including bland delicate desserts andmilk products, as well as meat products, cereals, gravies, sauces,soups, baked goods, and the like.

The improved, edible, soy protein concentrates of this in vention, whencompared with a concentrate of U.S. Pat. No. 2,881,076, havesubstantially the same protein content, and, can provide outstandingemulsifying and water-binding properties. Further, the proteinconcentrate of this invention has less of the characteristic beany orchalky taste or flavor, and beany odor and color, which makes suchconcentrate products more suitable for use in foods for humans,including bland delicate foods. Still further, when the dried, soyprotein concentrate of this invention is suspended in water, a moretranslucent product results and the insoluble hemicellulose has less ofa tendency to settle upon standing.

Briefly, my invention contemplates a process whereby soybean proteinmaterials (e.g., defatted or deoiled soybean material), includingsoybean flakes or flour, is extracted with water or water havingalkaline material (e.g., sodium sulfite, sodium carbonate, caustic orsodium carbonate solution), so that the pH of the soy protein materialis above the vicinity of the isoelectric pH of the glycinin content(i.e., pH of about 4 to 4.8), preferably at a pH of at least about 7.The use of an aqueous alkaline solution having sodium sulfite isparticularly desired because the sulfite serves as an alkaline bufferand protein preservative. The liquid extract, which includessoluble'protein and undesired, characteristic beany or chalky taste orflavor, and beany .odor and color conferring ingredients, is removed orseparated from the insoluble, fibrous residue. 1 prefer that theinsoluble, precipitated, fibrous residue be subjected to additionalextractions or washing with aqueous alkaline solution and/or water. Atleast part of any remaining liquid extract is removed from the fibrousresidue by a centrifuging, screening, or filtering operation. Theresulting washed, insoluble, fibrous residue has about 50 to 65 percentby weight protein on a dry basis.

The separated liquid extract from the initial extraction step at a pHabove the vicinity of the isoelectric pH of the glycinin content of thesoybean material, which has soluble protein, and, if desired, the liquidextract from the additional extractions or washing, is lowered oracidified (e.g., with acetic acid, hydrochloric acid, the combination ofhydrochloric acid and sodium sulfite, sulfuric acid, sulfurous acid, andphosphoric acid) to a pH in the vicinity of the isoelectric pH of theglycincin content (i.e., pH of about 4 to 4.8). The characteristic beanyor chalky taste or flavor, and beany odor and color conferringingredients and soluble sugars and nitrogen-containing bodies arepresent in the resulting liquid whey, and the whey is removed from theresulting precipitated, soy isolate curd which contains glycininprotein. If desired, the precipitated isolate may be subjected toadditional extractions or washing with an aqueous acidified solutionand/or water. The separation and recovery of the protein isolate may beaccomplished by centrifuging, screening or filtering operations. Therecovered, wet, soy protein isolate curd contains, for example, about 90to 97 percent by weight protein on a dry basis.

The resulting soybean protein isolate is then combined, in desiredproportions, with the washed, insoluble, fibrous residue from theextraction of the soybean material at a pH above the vicinity of theisoelectric pH of the glycinin content to produce a wet, proteinconcentrate.

An edible, inorganic alkali or inorganic buffering agent or admixture(e.g., sodium carbonate, sodium bicarbonate, sodium hydroxide, disodiumphosphate, trisodium phosphate, sodium tripolyphosphate, sodiumtetrapyrophosphate, the analogous potassium phosphates, and ammoniumhydroxide) is added to the soy protein concentrate material to raiseneutralize) the pH of the concentrate to within the range of from about5.5 to 10.5.

The resulting wet, neutralized, soy protein concentrate product, whichmay be in the form of dough, is then dried.

The drying operation can be accomplished, for example, by spray dryingthe wet concentrate, or by drying a thin layer of the wet concentratewhile it is subjected to a vacuum.

If desired, the fibrous residue and/or soy protein isolate curd may besubdivided or comminuted in a wet state before they are combined to formthe wet concentrate, or the concentrate may be subdivided before orafter it is dried.

Although soybean flour and the like can be used in my process, there areeconomic advantages in using soybean flakes.

The resulting, essentially dry, particulate, highly proteinaceousconcentrate composition has about 60 to percent by weight protein on adry basis, and is edible, uniformly palatable, bland, nutritious,debittered, and free of undesired, characteristic beany or chalky tasteor flavor, and beany odor and color. The soy protein concentrate hasoutstanding emulsifying and water-binding characteristics, provideddrying is conducted under conditions wherein substantial denaturing doesnot occur. When the soy protein is not to be used in meat products whereemulsifying and water-binding characteristics is sought, denaturing ofthe protein may not be objectionable.

The following examples are for purposes of illustration only, and myinvention is not necessarily limited thereto.

EXAMPLE 1 One-hundred g. of defatted soybean flakes were suspended in500 ml. of water to which was added 0.5 g. of sodium sulfite. The pH ofthe slurry was adjusted with 50 percent by weight aqueous caustic sodato a pH of 8 and was agitated for 10 minutes, followed by the screeningof the material through an 8 mesh screen. The flakes were washed on thescreen with water and were then suspended in 500 ml. of water and againagitated for a few minutes, followed by screening and washing withwater.

The solids content of the washed fibrous flakes or residue was 10.6percent by weight and the flakes had a protein content of 6.2 percent byweight which on a dry basis was calculated as 58.3 percent by weightprotein. The weight of the dry flakes on dry solids basis was 30.4 g.which was calculated as 3 3 .8 percent by weight of the initial soybeanflakes.

The liquor extracts from the screening steps were combined. Hydrochloricacid was added to the extract to adjust its pH to 4.2. The soy proteinisolate curd was allowed to settle and the supernatant liquid whey wasdecanted off. This procedure was repeated two times to purify the soyprotein isolate curd.

The solids content of the washed isolate curd was 6.4 percent by weightand the protein content was 5.7 percent by weight which is equivalent topercent by weight protein. The weight of the protein curd was 500 g.which was calculated as 32 g. of solids, indicating 35.5 percent byweight of the starting soybean material was recovered in the proteincurd fraction.

The discarded liquid whey from the process was combined to a totalvolume of 1,530 cc. The solids content was 1.41 percent by weight whichwas calculated as 21.4 g. of solids or 24 percent by weight of thestarting soybean material.

The soy protein isolate curd and the washed soy protein flakes orresidue were combined to form a soy protein concentrate. The concentratewas centrifuged, and the supernatant liquid was discarded.

The solids content of the recovered centrifuged concentrate material was21.7 percent by weight and the protein content was 16.0 percent byweight which was calculated as 73.5 percent by weight protein on a drybasis in this fraction. The weight of the centrifuged concentratematerial was 302.5 g. which was calculated as 65.5 g., indicating thatin the combined fraction of the washed soy protein flakes and the washedsoy protein isolate curd, 73 percent by weight of the starting soybeanmaterial was recovered in the concentrate.

The soy protein concentrate material from the centrifuge was thenneutralized with a 10 percent aqueous sodium hydroxide solution to a pHof 6.5. The concentrate product had the appearance of a heavy stickybatter. It was placed on trays and dried at 130 F. under vacuum. As soonas the vacuum was pulled, the viscous material expanded to approximatelyfivefold its original volume. This expansion of the concentratepermitted rapid drying similar to foam drying.

The dried soy protein concentrate of this example was lighter and hadless color than a dried soy protein concentrate made in accordance withU.S. Pat. No. 2,881,076. Water was added to separate portions of thedried soy protein concen trate material produced in this example and adry soy protein concentrate made in accordance with U.S. Pat. No.2,881,076, to provide 5 percent by weight concentrate samples that weretasted. The concentrate of this example had less of a beany or chalkytaste or flavor. In addition, it was noted 1 that when the dried soyprotein concentrate product of this example was suspended in water, theresulting product was more translucent and there was less of a tendencyof the insoluble hemicellulose to settle on standing, than when thedried, neutralized soy protein concentrate of US. Pat. No. 2,881,076 wassuspended in water.

An analysis was made of the dried soy protein concentrate products madein accordance with this example and U.S. Pat. No. 2,881,076. The resultsobtained were as follows:

Concentrate made in accordance with Concentrate made in One-hundred g.of defatted soy flakes were suspended in 600 ml. of water to which 0.5g. of sodium bisulfite was added. 0.7 ml. of a 50 percent by weight ofan aqueous caustic soda solution (50 percent caustic soda) was added toadjust the pH to 7.99. The slurry was agitated for 30 minutes.

The slurry was placed on a 12 mesh screen. The recovered insolublefibrous soy protein flakes were washed with 100 ml. of water. Anadditional 400 ml. of water were added to the recovered insolubleflakes. The slurry was then screened again through the 12 mesh screen,and again washed with 100 ml. of

water.

The analysis of the resulting recovered washed insoluble soy proteinflakes or residue was as followed:

Washed insoluble Soy Protein Flakes or Residue Weight ofWet Material 276g. Solids 12.2% Protein (Dry Basis) 62.4% Weight of Washed Soy Flakes(Dry Basis] 33.4% Percentage Material From Soy Flakes 36.8%

The washed insoluble soy protein flakes or residue was slightly morethan one-third of the weight of the starting defatted soybean flakes,and the extraction process removed protein and other ingredients. Thefinished washed soy flakes were still quite rich in protein content.

Nine-hundred fifty ml. of the proteinaceous liquor extract from theabove extraction steps were collected. 4.85 ml. of 22 B. hydrochloricacid were added to the liquor to bring the pH down to 4.2. The soyprotein isolate curd was allowed to settle to slightly less than half ofthe volume. The supernatant whey was decanted off, and the isolate wasthen brought back to the original volume following the same procedure.This process was repeated three times and then the settled proteinisolate curd slurry was transferred to centrifuge tubes and centrifugedfor 15 minutes at 2,500 r.p.m. The clear supernatant liquid was decantedoh and added to the discarded liquid whey fraction. The analysis of theresulting insoluble soy protein isolate curd paste was as follows:

insoluble Soy Protein Isolate Curd Paste Weight of Protein Paste l 12 g.Solids 30.3% Protein Content of the Paste 28.6% Protein Content (DryBasis) 94% Weight ofthe Protein Isolate (Dry Basis) 33.6 g. PercentageMaterial From Original Soybean Material 37.6%

The total volume of soy whey collected during the processing was 2,130ml. and the solids content was 1.21 per cent by weight which wascalculated as 25.8 g. of solids in the whey which is equivalent to 28percent by weight of the starting soybean material on a dry basis.

The washed soy protein flakes were combined with the pasty isolate curdand the resulting soy protein concentrate was mixed until substantiallyuniform.

The solids content of this concentrate blend was 16.7 percent by weightand the pH was 5.3. It required 2.5 ml. of 15 percent by weight of anaqueous caustic soda solution to bring the pH up to 6.7. The productbecame a. very heavy doughlike mass. This material was then placed in athin layer of about one-eighth to one-fourth in. thickness on analuminum tray. The tray was then placed overnight in a vacuum oven at136 F. As soon as the vacuum was pulled, it was noted that the volume ofthe paste increased or foamed to about five to tenfold its originalvolume.

A comparison of the soy protein concentrates made in accordance withthis example and the dried, neutralized soy protein concentrate of U.S.Pat. No. 2,881,076 provided the following data:

Concentrate made in accordance with Concentrate made index Uponcomparing the viscosity of the concentrate products made in accordancewith this example and U.S. Pat. No. 2,881.067, it was found that theprocess: of this example gave substantially higher viscosity which, ofcourse, is very desirable where emulsification is sought. In making thiscomparison, 15 g. of each of these concentrate products were added toseparate containers having ml. of water, and the resulting products wereplaced in a Waring Blender at low speed for 2 minutes. Time was allowedfor the foam to break and the viscosity was determined using theBrookfield viscometer. The results were as follows:

Viscosity in Centiposcs Dried Neutralized Soy Protein Concentrate Madein Accordance with U.S. Pat. No. 2,881,076 Soy Protein Concentrate Madein Accordance with This Example Five experienced tasters out of the sixdefinitely noted the concentrate product made in accordance with US.Pat. No. 2,881,076 had a decidedly greater beany taste or flavor.

The forms of the invention herein shown and described are to beconsidered only as illustrative. it will become apparent to thoseskilled in the art that other modifications may be made therein withoutdeparture from the invention or scope of the appended claims.

lclaim:

l. A method for producing or recovering an essentially dry, particulate,edible, nutritious, uniformly palatable, bland, debittered, soy proteinconcentrate suitable for use in food products for humans, whichcomprises extracting soybean material with a liquid extracting medium ata pH above the vicinity of the isoelectric pH of the glycinin content ofsaid material to produce an insoluble, fibrous residue and a liquidextract having undesired soluble beany-taste-conferring bodies andsoluble protein, separating the liquid extract from the fibrous residue,washing and recovering the resulting insoluble, fibrous residue free ofundesired beany-taste-conferring bodies, lowering the pH of said liquidextract to a pH in the vicinity of the isoelectric pH of the glycinincontent present therein to precipitate soy protein isolate and produceliquid whey having the undesired beany-taste-conferring bodies,recovering the precipitated protein isolate which is free of undesiredbeany-taste-conferring bodies, forming a neutralized mixture of adesired proportion of said recovered, fibrous residue and recovered,protein isolate to produce a soy protein concentrate, and drying the soyprotein concentrate without substantially insolubilizing the protein, toproduce said essentially dry, particulate, bland, soy proteinconcentrate free of undesired, characteristic beany taste and having apH within the range of about 5.5 to 10.5.

2. The method of claim 1 wherein said drying is conducted under a vacuumwhile the wet, soy protein concentrate is in an expanded state.

3. The method of claim 1 wherein the concentrate is subdivided.

4. The method of claim 1 wherein said soy protein concentrate containsabout 60-85 percent by weight protein on a dry basis.

5. A method for producing or recovering from soybean material anessentially dry, particulate, soy protein characterized by being anedible, nutritious, uniformly palatable, bland, debittered, soy proteinconcentrate free of undesired, characteristic beany or chalky taste orflavor, and beany odor and color, and suitable for use in food productsfor humans, which involves extracting soybean material with an aqueousextracting medium at a pH of at least about 7 to provide an insoluble,fibrous residue and a liquid extract having soluble protein andundesired, characteristic beany or chalky taste or flavor, and beanycolor and odor conferring bodies, separating the highly proteinaceousextract from the fibrous residue, washing and recovering the insoluble,fibrous residue which has about 50 to 60 percent by weight protein on adry basis and is free of said undesired, characteristic bodies, reducingthe pH of the separated liquid extract with an acidified, aqueous mediumto a pH in the vicinity of the isoelectric pH of the glycinin contenttherein to precipitate insoluble, soy protein isolate curd from theliquid extract while the undesired, characteristic beany or chalky tasteor flavor, and beany color and odor conferring bodies are in theresulting liquid whey in a soluble form, separating from the whey theprecipitated, protein isolate curd, recovering the insoluble, proteinisolate which is free of said undesired, characteristic bodies,combining insoluble, fibrous residue with insoluble, more proteinaceous,soy protein isolate to produce a wet, soy protein concentrate havingabout 60 to percent by weight protein on a dry basis, adjusting the pHof the protein concentrate to a pH of about 5.5 to 10.5, and drying thewet protein concentrate without substantially insolubilizing theprotein, to produce said essentially dry, particulate, bland, proteinconcentrate free of undesired, characteristic beany or chalky taste orflavor, and beany odor and color.

6. The method of claim 5 wherein the concentrate is subdivided.

7. The method of claim 5 wherein said drying is conducted under a vacuumwhile the wet soy protein concentrate is in an expanded state.

8. The method of claim 5 wherein about35-37 percent by weight of thesoybean material is recovered as said fibrous residue and about 35-38percent by weight of the soybean material is recovered as said soyprotein isolate.

9. A method for producing or recovering an essentially dry, particulate,edible, nutritious, uniformly palatable, bland, debittered, soy proteinconcentrate suitable for use in food products for humans, whichcomprises extracting soybean material with a liquid extracting medium ata pH above the vicinity of the isoelectric pH of the glycinin content ofsaid material to produce an insoluble, fibrous residue and a liquidextract having undesired soluble beany-taste-conferring bodies andsoluble protein, separating the liquid extract from the fibrous residue,washing and recovering the resulting insoluble, fibrous residue free ofundesired beany-taste-conferring bodies, lowering the pH of said liquidextract to a pH in the vicinity of the isoelectric pH of the glycinincontent present therein to precipitate soy protein isolate and produceliquid whey having the undesired beany-taste-conferring bodies,recovering the precipitated protein isolate which is free of undesiredbeany-taste-conferring bodies, combining a desired proportion of saidrecovered, fibrous residue and recovered, protein isolate to produce awet soy protein concentrate, raising the pH of the protein concentrateto a pH of about 5.5 to 10.5 if the pH thereof is not already in thatrange, and drying the wet, soy protein concentrate without substantiallyinsolubilizing the protein, to produce said essentially dry,particulate, bland, soy. protein concentrate free of undesired,characteristic beany taste.

10. The method of claim 9 wherein said drying is conducted under avacuum while the wet, soy protein concentrate is in an expanded state.

11. The method of claim 9 wherein the concentrate is su bdivided.

12. The method of claim 9 wherein said soy protein concentrate containsabout 60-85 percent by weight protein on a dry basis.

2. The method of claim 1 wherein said drying is conducted under a vacuumwhile the wet, soy protein concentrate is in an expanded state.
 3. Themethod of claim 1 wherein the concentrate is subdivided.
 4. The methodof claim 1 wherein said soy protein concentrate contains about 60-85percent by weight protein on a dry basis.
 5. A method for producing orrecovering from soybean material an essentially dry, particulate, soyprotein characterized by being an edible, nutritious, uniformlypalatable, bland, debittered, soy protein concentrate free of undesired,characteristic beany or chalky taste or flavor, and beany odor andcolor, and suitable for use in food products for humans, which involvesextracting soybean material with an aqueous extracting medium at a pH ofat least about 7 to provide an insoluble, fibrous residue and a liquidextract having soluble protein and undesired, characteristic beany orchalky taste or flavor, and beany color and odor conferring bodies,separating the highly proteinaceous extract from the fibrous residue,washing and recovering the insoluble, fibrous residue which has about 50to 60 percent by weight protein on a dry basis and is free of saidundesired, characteristic bodies, reducing the pH of the separatedliquid extract with an acidified, aqueous medium to a pH in the vicinityof the isoelectric pH of the glycinin content therein to precipitateinsoluble, soy protein isolate curd from the liquid extract while theundesired, characteristic beany or chalky taste or flavor, and beanycolor and odor conferring bodies are in the resulting liquid whey in asoluble form, separating from the whey the precipitated, protein isolatecurd, recovering the insoluble, protein isolate which is free of saidundesired, characteristic bodies, combining insoluble, fibrous residuewith insoluble, more proteinaceous, soy protein isolate to produce awet, soy protein concentrate having about 60 to 85 percent by weightprotein on a dry basis, adjusting the pH of the protein concentrate to apH of about 5.5 to 10.5, and drying the wet protein concentrate withoutsubstantially insolubilizing the protein, to produce said essentiallydry, particulate, bland, protein concentrate free of undesired,characteristic beany or chalky taste or flavor, and beany odor andcolor.
 6. The method of claim 5 wherein the concentrate is subdivided.7. The method of claim 5 wherein said drying is conducted under a vacuumwhile the wet soy protein concentrate is in an expanded state.
 8. Themethod of claim 5 wherein about 35-37 percent by weight of the soybeanmaterial is recovered as said fibrous residue and about 35-38 percent byweight of the soybean material is recovered as said soy protein isolate.9. A method for producing or recovering an essentially dry, particulate,edible, nutritious, uniformly palatable, bland, debittered, soy proteinconcentrate suitable for use in food products for humans, whichcomprises extracting soybean material with a liquid extracting medium ata pH above the vicinity of the isoelectric pH of the glycinin content ofsaid material to produce an insoluble, fibrous residue and a liquidextract having undesired soluble beany-taste-conferring bodies andsolUble protein, separating the liquid extract from the fibrous residue,washing and recovering the resulting insoluble, fibrous residue free ofundesired beany-taste-conferring bodies, lowering the pH of said liquidextract to a pH in the vicinity of the isoelectric pH of the glycinincontent present therein to precipitate soy protein isolate and produceliquid whey having the undesired beany-taste-conferring bodies,recovering the precipitated protein isolate which is free of undesiredbeany-taste-conferring bodies, combining a desired proportion of saidrecovered, fibrous residue and recovered, protein isolate to produce awet soy protein concentrate, raising the pH of the protein concentrateto a pH of about 5.5 to 10.5 if the pH thereof is not already in thatrange, and drying the wet, soy protein concentrate without substantiallyinsolubilizing the protein, to produce said essentially dry,particulate, bland, soy protein concentrate free of undesired,characteristic beany taste.
 10. The method of claim 9 wherein saiddrying is conducted under a vacuum while the wet, soy proteinconcentrate is in an expanded state.
 11. The method of claim 9 whereinthe concentrate is subdivided.
 12. The method of claim 9 wherein saidsoy protein concentrate contains about 60-85 percent by weight proteinon a dry basis.